Death In Athletes Research Articles

Mechanistic Insights Into RNA Splicing As A Trigger For Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic cardiac disease that causes sudden death in young adults and athletes. ARVC is termed a “disease of the desmosome” as 40% of mutations in ARVC patients are found in the cardiac desmosomal components, with plakophilin‐2 (PKP2) being the most frequently mutated desmosomal gene in ARVC. Evidence from humans suggests that altered RNA splicing may be a critical mechanism through which PKP2 patient genetics drive ARVC. Studies have suggested that approximately one third of all human disease‐causing mutations are a result of defects in RNA splicing; highlighting the importance of testing the relevance of this mechanism in human ARVC. However, there are no models and limited mechanistic insights into how mutations in RNA splicing impact ARVC disease pathogenesis. We hypothesize that RNA splicing mutations in PKP2 are sufficient to recapitulate classic disease features associated with human ARVC and can provide valuable mechanistic insight into how altered RNA splicing impacts disease. Through CRISPR‐Cas9 we generated a novel knock‐in mouse model harboring a human equivalent PKP2 mutation (IVS10‐1 G>C) that impacts RNA splicing and is sufficient to recapitulate all classic ARVC disease features. PKP2 homozygous mutant (PKP2 Hom) mice are viable at birth yet display adult hallmarks of ARVC including ventricular arrhythmias, right and left ventricular dysfunction, and fibro‐fatty replacement of myocardium leading to sudden death. RNA and sequencing analyses of exons spanning the PKP2 mutation site reveals a larger PKP2 transcript that retains a 54 base pair portion of the intronic sequence in PKP2 Hom hearts. However, RNA analysis of exons outside the PKP2 mutation site reveals PKP2 RNA transcripts at similar levels to wild type PKP2, suggesting that total RNA levels are not impacted by the mutation. Instead, we show that PKP2 Hom hearts express a higher molecular weight mutant PKP2 protein in the absence of endogenous PKP2. Analysis of PKP2 Hom neonatal hearts and cardiomyocytes reveal early desmosomal protein loss coupled with a susceptibility to baseline arrhythmias in the absence of overt cardiac disease features at this stage (e.g., no changes in heart weight/body weight ratios, no upregulation of cardiac stress and fibrotic markers). We provide a novel mouse model that highlights the sufficiency and molecular consequences of a PKP2 RNA splicing mutation that triggers all of the classic early and adult onset disease features associated with human ARVC.Support or Funding InformationNational Science Foundation (Graduate Research Fellowship Program), National Institutes of Health (NIH R01, HL142251‐A1)

Mid-septal accessory pathway in a young professional athlete: when and how to ablate?

Wolf-Parkinson-White (WPW) syndrome is responsible for 1% of all deaths in athletes. Considering the increased risk of sudden cardiac death (SCD) in athletes compared to general population, a comprehensive risk stratification is crucial. Both American and European guidelines recommend electrophysiology (EP) study for risk assessment and catheter ablation as the fi rst-line treatment in athletes with WPW syndrome. Radiofrequency (RF) catheter ablation is the routine treatment for most accessory pathways (AP). However, cryo-energy ablation is recommended for APs located close to the atrioventricular node, in particular mid-septal and superoparaseptal, because of the increased risk of complete atrioventricular block with RF ablation. Depending on the European or American guidelines, athletes should be granted clearance for competitive sports 1 month after the procedure if free of symptoms and without pre-excitation recurrence on ECG.

Athletes ECG Stress Characteristics in Division II College Athletes: A Preliminary Analysis

Two-thirds of sudden cardiac deaths are attributable to underlying cardiovascular conditions in young collegiate athletes. A 12-lead exercise stress test is a screening tool that can detect these abnormalities that may predispose collegiate athletes to sudden cardiac death, and can ensure athletes meet the physical demands of training and competition. The purpose of this study was to evaluate the electrocardiographic (ECG) characteristics of Division II collegiate athletes using the Seattle Criteria. Fifty two athletes (males = 26; females = 26) of various ethnicities (Caucasian = 65%, Latino/Hispanic = 20%, and African American = 15%); from soccer (27%), tennis (17%), basketball (15%), softball (14%), cross country (9%), volleyball (6%), football (6%), and swimming (6%) completed cardiovascular screening with resting and exercise 12-lead ECG analysis. ECG abnormalities and anthropometrics were compared across race, gender, and sports using an ANOVA. Chi-square analysis was used to test for differences in the frequency of ECG findings across gender, race, and sports. Although sport was not a predictor for an abnormal ECG, 73% of the athletes presented with athletes’ heart configuration, which was significantly higher in males than females (P = 0.02). The highest occurrence of these adaptations was observed in 100% of Latino/Hispanic athletes, compared to 75% of African American and 64% of Caucasian athletes. With newer and more sensitive ECG screening criteria, the prevalence of false-positive tests is declining. Future research should focus on advancing the sensitivity and specificity of ECG interpretation in more diverse athletic populations regarding race and gender. The increasing incidence of sudden cardiac death in collegiate athletes warrants future research that evaluates the impact of implementing the 12-lead ECG as a standard screening tool for collegiate athletes.

How to interpret right ventricular remodeling in athletes.

Long‐lasting athletic training induces an overload on the heart that leads to structural, functional, and electrical adaptive changes known as the “athlete's heart.” The amount of this heart remodeling has been traditionally considered balanced between the left and the right heart chambers. However, during intense exercise, the right heart is exposed to a disproportional afterload and wall stress which over a long period of time could lead to more pronounced exercise‐induced changes. Highly trained athletes, especially those involved in endurance sport disciplines, can develop marked right ventricular (RV) remodeling that could raise the suspicion of an underlying RV pathology including arrhythmogenic cardiomyopathy (ACM). The distinction between physiological and pathological RV remodeling is essential as ACM is a common cause of sudden cardiac death in athletes, and high‐intensity exercise training has demonstrated to accelerate its phenotypic expression and worsen its prognosis. The distinction between physiological and pathological RV remodeling is essential since ACM is a common cause of sudden cardiac death in athletes, and high‐intensity exercise training has demonstrated to accelerate the phenotypic expression and worsen the prognosis. This article outlines the physiological adaptation of the RV to acute exercise, the subsequent physiological structural and functional changes induced by athletic training and provides useful tips of how to differentiate between physiological RV remodeling and a cardiomyopathy phenotype.

A UNIQUE RCA: AN ANOMALOUS ORIGIN WITH A COURSE BETWEEN THE GREAT VESSELS

Anomalous coronary artery from opposite sinus (ACAOS) with malignant inter-arterial course can cause sudden cardiac death in young athletes. However, older patients ACAOS are less predisposed to adverse cardiac events. 76-year-old female presents for evaluation of exertional chest pain. Physical

Sudden death of athletes in nursing practice

The article deals with the epidemiology and main causes of sudden cardiac death in professional athletes and people participating in sports as amateurs. Pathogenesis of the main nosologies, as well as preventive measures and emergency care in case of life-threatening conditions are described.

Alterações anatômicas coronarianas mais frequentes

Background Coronary artery anomalies represent an array of malformations of the vessels responsible for myocardial perfusion, with a prevalence of 1% in the general population. Mostly asymptomatic, they are diagnosed during routine tests. When symptomatic, they are the second major cause of sudden death in young athletes. Our study aimed to assess the most commonly found coronary vessel anatomic anomalies during cardiac catheterization procedures. Methods An analytic cross-sectional study was performed assessing the medical charts of patients submitted to [...]

Outcomes in Anomalous Aortic Origin of a Coronary Artery Following a Prospective Standardized Approach

Anomalous aortic origin of a coronary artery (CA) is the second leading cause of sudden cardiac death in young athletes. Management is controversial and longitudinal follow-up data are sparse. We aim to evaluate outcomes in a prospective study of anomalous aortic origin of CA patients following a standardized algorithm. Patients with anomalous aortic origin of a CA were followed prospectively from December 2012 to April 2017. All patients were evaluated following a standardized algorithm, and data were reviewed by a dedicated multidisciplinary team. Assessment of myocardial perfusion was performed using stress imaging. High-risk patients (high-risk anatomy-anomalous left CA from the opposite sinus, presence of intramurality, abnormal ostium-and symptoms or evidence of myocardial ischemia) were offered surgery or exercise restriction (if deemed high risk for surgical intervention). Univariate and multivariable analyses were used to determine predictors of high risk. Of 201 patients evaluated, 163 met inclusion criteria: 116 anomalous right CA (71%), 25 anomalous left CA (15%), 17 single CA (10%), and 5 anomalous circumflex CA (3%). Patients presented as an incidental finding (n=80, 49%), with exertional (n=31, 21%) and nonexertional (n=32, 20%) symptoms and following sudden cardiac arrest/shock (n=5, 3%). Eighty-two patients (50.3%) were considered high risk. Predictors of high risk were older age at diagnosis, black race, intramural course, and exertional syncope. Most patients (82%) are allowed unrestrictive sports activities. Forty-seven patients had surgery (11 anomalous left CA and 36 anomalous right CA), 3 (6.4%) remained restricted from sports activities. All patients are alive at a median follow-up of 1.6 (interquartile range, 0.7-2.8) years. In this prospective cohort of patients with anomalous aortic origin of a CA, most have remained free of exercise restrictions. Development of a multidisciplinary team has allowed a consistent approach and may have implications in risk stratification and long-term prognosis.

Current paradigms in the prehospital care of exertional heat illness: A review

Exertional heat illness, including muscle cramps, heat syncope, heat exhaustion, and heat stroke, occur each year in athletes and military soldiers. Exertional heat stroke, the most concerning type of exertional heat illness, is a life-threatening condition defined clinically by a core body temperature greater than 104° F (40°C) and central nervous system dysfunction. Heat stroke may lead to multiorgan failure and death and is one of the leading causes of nontraumatic death in athletes participating in outdoor activities. Current recommendations are discussed regarding prehospital and first responder care of exertional heat illness, particularly heat stroke, with an emphasis on rapid recognition, assessment, and implementation of cooling and advanced care strategies. This overview is of particular interest to orthopaedic team physicians who often are first responders on the field.

Hypertrophic cardiomyopathy

Abstract:Hypertrophic cardiomyopathy (HCM), a common congenital heart disease, is the leading cause of sudden cardiac death in adolescents, young adults, and athletes. Older adults with HCM are less likely to experience sudden cardiac death, but their quality of life can be impaired. This article di

Comparison of wet bulb globe temperature measured on-site vs estimated and the impact on activity modification in high school football.

Exertional heat stroke is one of the top three causes of death in young athletes, particularly high school football players. Despite evidence that these deaths are completely avoidable with appropriate prevention and treatment, deaths still occur at an alarming rate. Wet bulb globe temperature (WBGT) is the preferred method of both the National Athletic Trainers' Association and American College of Sports Medicine to measure heat intensity. Based on the WBGT, activity modification guidelines (AMG) dictate work-to-rest ratios, activity levels and duration, protective equipment worn, and length and frequency of hydration breaks. Due to the cost of handheld WBGT monitors, smartphone apps that estimate WBGT have been considered an alternative. However, it is unclear how WBGT values estimated by these smartphone apps compare to those measured on-site using handheld WBGT monitors. We compared WBGT values estimated by a commercial smartphone app to those taken on-site at the same time and place. Thirteen athletic trainers measured WBGT in the field during high school football practices over a three-month season in North Central Florida. A paired sample t-test indicated the smartphone app significantly overestimated WBGT (29.0°C ± 4.1°C) compared to on-site measures (26.4°C ± 3.2°C) ( r =0.580; t(943)=-23.38, p <0.0001). The smartphone app-estimated values were consistently greater than on-site measures, resulting in potentially unnecessary activity modifications and cancellations if the app was used in place of on-site handheld WBGT monitors. Despite being significantly cheaper than handheld WBGT monitors, at this time, smartphone apps are not ready for widespread use to guide activity modification decisions.

Sudden Cardiac Death in Famous Athletes, Lessons Learned, Heterogeneity in Expert Recommendations and Pitfalls of Contemporary Screening Strategies.

Sudden cardiac death (SCD) in competitive athletes, though relatively uncommon, invariably leads to controversy. Specific limitations of an extensive screening process include lack of robust evidence to support prevention of SCD, poor cost-effectiveness and uncertain downstream implications of a positive screening test. An emerging body of evidence points to enhanced neurologically intact survival to hospital discharge when automated external defibrillators (AEDs) are used in a timely manner following sudden cardiac arrest (SCA). A viable alternative to an expansive screening process could be a robust secondary prevention system comprising of improvements in AED availability, stringent enforcement of CPR training in athletes and trainers to provide timely and effective resuscitation to reduce death following SCA. This strategy could widen the window to diagnose and treat the underlying etiology and prevent recurrence of SCA while also offering financial feasibility. Restricting athletes from competitive sports is a difficult decision for physicians owing to a lack of well-defined cutoffs for acceptable and prohibitive risk from pathology predisposing to SCD, especially in the absence of a protective medico-legal framework. In this review, we highlight a few cases that generated intense scrutiny by the public, media and medical professionals about the efficacy, feasibility and pitfalls of the existing screening process to diagnose cardiovascular pathology predisposing to SCD. Furthermore, contrasting approaches to screening, diagnosis and downstream workup protocols between the European Society of Cardiology and the American Heart Association are analyzed.

Exercise Recommendations for the Athlete With Coronary Artery Disease.

We provide a framework for formulating exercise prescriptions for those with CAD in order to achieve the "optimal" dose of exercise for each individual. Multiple epidemiological studies demonstrate that exercise is inversely associated with atherosclerotic coronary artery disease (CAD), yet the risk of an acute coronary event is transiently elevated during vigorous exercise. In turn, CAD is the most common cause of exercise-related sudden cardiac death (SCD) in older athletes. When prescribing exercise recommendations for athletes with CAD, we should maintain equipoise between the benefits derived from sports participation and the risk of an adverse cardiac event. Athletes are not immune from atherosclerotic CAD, and we should perform risk assessments regardless of physical and athletic prowess. Cardiopulmonary exercise testing may be a useful tool to develop individualized exercise regimens for athletes with CAD.

Reduce injuries, limit liability by applying interassociation recommendations

The National Collegiate Athletic Association's Sport Science Institute and the College Athletic Trainers’ Society recently published a helpful document, “Interassociation Recommendations: Preventing Catastrophic Injury and Death in Collegiate Athletes.”

P4422Myocarditis: a deceitful but not infrequent athletes' enemy

Abstract Introduction Myocarditis represents a not negligible cause of sudden death (SD) in athletes, representing the cause of 4%-14% cardiac arrests and deaths in athletes. Preparticipation screening including 12-leads basal electrocardiogram could drastically reduce SD in athletes and screening programs are therefore now recommended by most medical and sport association. At the moment, no data in literature are available about incidence of concealed myocarditis in athletes but there is general consensus about disqualification from competitive sport in the presence of myocardial fibrosis (MF). Purpose Purpose of our study was to quantify incidence of MF consistent with past myocarditis in athletes that referred to our Sport Cardiology Center for ventricular arrhythmias (VA) +/− repolarization abnormalities (RA) detected at preparticipation screening. Methods In our study we retrospectively evaluated all athletes with VA +/− RA and we quantified how many were found to have MF consistent with myocarditis at cardiac MRI. Furthermore, we evaluated characteristics of presentation in terms of clinical symptoms of myocarditis and frequency and morphology of VA. Finally, we analyzed findings of invasive diagnostic workout when performed. Results In the last two years we evaluated 111 athletes for VA +/− RA and we found MF consistent with myocarditis in 18 (16%) of them. Only 2/18 referred past febrile status probably correlated with myocarditis and 1 had symptoms consistent with acute myocarditis. Number of VA was not correlated with MF fibrosis, while polymorphic VA and exercise-correlated VA were the most frequent finding. 5/18 (28%) had also rest and/or exercise induced RA. 10/18 (55%) athletes underwent electrophysiological study without any induction of arrhythmias. 7/18 (39%) underwent also electroanatomical mapping (EAM) with pathological findings in 5/7 (71%). All of these 5 underwent endomyocardial biopsy guided by EAM and in 2 cases bioptic findings were consistent with arrhythmogenic cardyomyopahty (ACM). All 18 athletes were disqualified from competitive sport as for Italian Sport Medicine protocols. Conclusion MF consistent with past myocarditis is a not infrequent finding in athletes with VA with or without RA. Morphology and exercise behavior of VA are the most important “alarm bell”, while VA number is not correlated with MRI pathological findings. Sometimes MF interpreted as consistent with past myocarditis is actually the manifestation of ACM. Identification of these diseases is of extreme importance for athletes' safety.

4251Results from the Hungarian Cardiac Magnetic Resonance Registry of Structural Heart Disease and Aborted Sudden Cardiac Death in Athletes

Abstract Introduction Sudden cardiac death (SCD) is the most common cause of death in athletes occurring usually during intensive training. Cardiac magnetic resonance (CMR) has a crucial role in the detection of structural myocardial abnormalities. Aims Our aim was to investigate the etiology of SCD and to estimate the prevalence of myocardial structural heart diseases among Hungarian athletes using CMR. Methods Between January 2011 and January 2019 we performed CMR scans on 228 athletes (199 males, age: 29.1±13.2) with suspected structural myocardial disease. Twelve athletes were investigated after aborted sudden cardiac death and normal coronary angiography. Results CMR confirmed the diagnosis of structural myocardial disease in 62 athletes (26.2%) (28.8±9.1 years, 59 male): hypertrophic cardiomyopathy (HCM) in 14 cases (22.6%), arrhythmogenic right ventricular cardiomyopathy (ARVC) in 9 cases (14.5%), noncompaction (NCCMP) in 6 cases (9.7%) and dilated cardiomyopathy (DCM) in 5 cases (8.1%). Subendocardial late gadolinium enhancement (LGE), reflecting myocardial scar, was typical of previous myocardial infarction (post MI) in 3 cases (5.5%). Acute myocarditis was found in 2 cases (3.6%). Nonischaemic LGE pattern was found in 20 cases (32.2%): patchy subepi-midmyocardial LGE suggesting previous myocarditis in 8 athletes, and with aspecific pattern in 12 athletes. Athletes with nonischaemic LGE had normal clinical and laboratory parameters without wall motion abnormalities, in their cases further investigations ruled out systemic disease. One athlete was diagnosed with Fabry-disease, one with coronary artery abnormality (anomalous origin of the left main coronary artery from the right sinus of Valsalva), one athlete showed pheochromocytoma-related Tako-Tsubo cardiomyopathy (each 1.6%). Five athletes with confirmed structural heart disease were investigated after sustained ventricular tachycardia, seven athletes after aborted SCD: ARVC (n=6), aspecific LGE pattern (n=4), HCM (n=1) and pheochromocytoma-related Tako-Tsubo cardiomyopathy (n=1) were diagnosed. RVOT movie of an ARVC pts Conclusion In our national CMR registry the most common structural alteration was nonischaemic fibrosis, the most common cardiomyopathy was HCM, and the leading cause of SCD in Hungarian competitive athletes was ARVC. The national registers are highly important for a better understanding the etiology and the geographical differences of SCD in athletes. Acknowledgement/Funding Project no. NVKP_16-1-2016-0017 has been implemented with the support provided from the National Research, Development and Innovation Fund of Hungary

P310Differentiation between arrhythmogenic right ventricular cardiomyopathy and athlete's heart using cardiac magnetic resonance based derived parameters and strain analysis

Abstract Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of sudden cardiac death in young athletes. However diagnosing ARVC in highly trained athletes may be complicated because of overlapping features such as elevated right ventricular (RV) end-diastolic volume index or T-wave inversion in precordial leads. The revised Task Force criteria contain no specific cut-off value for professional athletes. Additional CMR parameters and CMR deformation imaging may have an added diagnostic value in this special patient population. Our goal was to determine novel CMR parameters which can help to distinguish between ARVC and athlete's heart. CMR examination of ARVC patients with definite diagnosis based on the revised Task Force criteria (n=34; 41±13 y, 22 male) and healthy professional athletes (members of the Hungarian national water polo, canoing or rowing team performing minimum of 15 hours of training per week, n=34, 32±6 y, 22 male) was performed. We evaluated left and right ventricular end-systolic, end-diastolic (EDVi) and stroke volume index, ejection fraction (EF) and mass. We established derived parameters such as ejection fraction ratio (LVEF/RVEF) and end-diastolic volume ratio (LVEDV/RVEDV). Global and regional strain analysis for the right ventricle was performed using feature tracking technique. Area under the ROC curves (AUC) of conventional and derived CMR parameters and CMR based strain values were analysed. There was no significant difference between RVEDVi of ARVC patients and athletes (124±17 vs 142±47), RVEF was lower in ARVC patients compared to athletes (56±5 vs 41±14%; p&lt;0.001). Significant differences were found between athletes and ARVC patients in LVEDV/RVEDV (0.96±0.08 vs 0.82±0.23), LVEF/RVEF (1.04±0.06 vs 1.41±0.56), global circumferential strain (−34.8±5.9 vs −25.2±12.2) and regional strain values such as midventricular RV strain (−31.5±10.2 vs −20.0±13.4) or midventricular RV strain rate (−1.37±0.56 vs −1.04±0.68), respectively. RVEF and LVEF/RVEF showed excellent (AUC of 0.9–1.0), RV global strain and RV midventricular strain values showed good diagnostic accuracy (AUC of 0.8–0.9), while RVEDVi showed poor diagnostic accuracy (AUC of 0.59). Consequently, in highly trained healthy athletes RVEDVi is in the range of major Task Force criteria, while CMR based derived parameters such as LVEDV/RVEDV or LVEF/RVEF and both global and regional RV strain parameters can be useful parameters in the differential diagnosis. Acknowledgement/Funding National Research, Development and Innovation Office (NKFIH) of Hungary (K 120277), ÚNKP-18-3-IV New National Excellence Program of Human Capacities.

Malignant Course of the Right Coronary Artery Originating from the Left Main Coronary Artery: An Odd Exit.

Introduction:Congenital coronary artery anomalies are quite uncommon with estimates ranging from 0.2% to 1.3% on coronary angiography. The rarity of these anomalies makes their diagnosis a formidable challenge. Variable arterial courses have been described. In this report, we present a case with unique arterial course, which starts as a hyperacute take-off of the right coronary artery (RCA) from the left main coronary artery (LMCA), with subsequent coursing, without external compression, between the right ventricular outflow tract and aorta. Our case is relevant to the concept of whether we should keep a reasonable index of suspicion for coronary artery anomalies during cardiac evaluations of patients undergoing non-cardiac surgeries.Clinical case:This is an asymptomatic 47-year-old African American female who presented for cardiac clearance for renal transplantation. She had a past medical history of hypertension, bronchial asthma, and former smoking of 10 years (quitting 15 years prior to presentation). She also has end-stage renal disease on hemodialysis. Cardiac workup revealed left ventricular hypertrophy on EKG, multi-chamber dilation seen on echo, and anomalous RCA course seen on CT coronary angiography. Cardiac catheterization revealed non-obstructive coronary artery disease of the LCX and RCA. After consulting with cardiothoracic surgery, conservative medical management was decided based on the patient’s risk stratification. She was advised to have close monitoring of her condition.Discussion:Coronary artery anomalies represent the second most common cause of sudden cardiac death in young athletes. At this time, the prevalence of right coronary artery (RCA) take off from the left coronary sinus occurs at a percentage of 0.019% to 0.49%. The RCA origination from the left main coronary artery (LMCA) accounts for only 0.65% of these anomalies. Our patient had high-risk anatomy consisting of a hyper-angulated take-off of the RCA from the LMCA as well as course between the pulmonary artery and right ventricular outflow tract (RVOT). CT coronary angiography is the most useful imaging modality that characterizes coronary artery anomalies. Although this patient exhibited no signs or symptoms of cardiorespiratory compromise, she warranted a full cardiac workup preoperatively that incidentally revealed a coronary anomaly. Recognition of this disease is critical for timely prevention of potential complications as well as discussion of goals of care. Guidelines for medical versus surgical management are available, but the management strategy should be individualized, with the highest consideration given to risk-benefit analysis.

Hypertrophic cardiomyopathy: New hope for an old disease.

Hypertrophic cardiomyopathy (HCM), a common congenital heart disease, is the leading cause of sudden cardiac death in adolescents, young adults, and athletes. Older adults with HCM are less likely to experience sudden cardiac death, but their quality of life can be impaired. This article discusses diagnostic criteria, treatments, and nursing interventions, including patient teaching, for adults with HCM.

Role of extensive diagnostic workup in young athletes and nonathletes with complex ventricular arrhythmias

Ventricular arrhythmias (VAs) are the most common cause of death in athletes. The differences in the electroanatomic substrate in athletes and nonathletes with complex VA are unknown. The purpose of this study was to compare the electroanatomic substrate of complex VA in athletes vs nonathletes. The study prospectively enrolled young athletes and nonathletes with VA. Patients underwent 2-dimensional echocardiography, cardiac magnetic resonance (CMR) imaging, coronary angiography, 3-dimensional electroanatomic mapping (3D-EAM), and 3D-EAM-guided endomyocardial biopsy (EMB). Follow-up included 24-hour electrocardiographic Holter or implantable cardioverter-defibrillator/loop recorder interrogation for VA recurrence. Thirty-three patients were enrolled: 18 competitive athletes (56%) and 15 nonathletes (44%). Left ventricular and right ventricular (RV) findings by echocardiography and CMR did not show structural disease. Nine athletes (50%) were asymptomatic compared to 1 nonathlete (7%; P <.05). Unifocal origin of VA was reported in 14 athletes (93%) and 17 nonathletes (94%). Athletes showed a larger RV unipolar than bipolar scar (18 ± 17 cm2 vs 3 ± 3.8 cm2; P = .04). Diagnostic yield of EMB was 50% in athletes and 40% in nonathletes. Among athletes, the final diagnosis was myocarditis in 2, arrhythmogenic ventricular right cardiomyopathy in 1, and focal replacement fibrosis in 1. Among nonathletes, EMB revealed focal replacement fibrosis in 4 cases. At median follow-up of 18.7 months, Kaplan-Meier curves showed lower VA recurrence in detrained athletes than nonathletes (53% vs 6%; P = .02). This study showed the need for extensive diagnostic workup in apparently healthy young patients with complex VA in order to characterize concealed cardiomyopathies.